Worst-Case Model for Considering Gaskets in Calculation of Shielding Effectiveness of Metallic Enclosures

Wideband worst-case model for estimation of effectiveness of electric and magnetic fields shielding by a metallic enclosure is developed. The model is intended to take into account a contribution of EMI gaskets that are mounted in gaps, joins between metal skin plates, and other apertures presented in a system (e.g., aircraft, ship, vehicle) body. The model is based on the generalization of the analytical model of electromagnetic field shielding by a metallic enclosure with combined walls (containing apertures of various shapes); this provides a high computational efficiency in the wide frequency band. Influence of the gasket structure and geometry on the shielding effectiveness is analyzed for the following high-usage gasket types: stamped or formed solid metal gaskets, gaskets in form of metal spring fingers, and knitted wire mesh. Validation of the developed model is carried out by comparison of results obtained in framework of the model with results of numerical simulations. For the validation, the ratios of the wavelength to the maximum dimension of the aperture with gasket are taken in the range from 1 to 1000.